Direct current machine stator

ABSTRACT

Stator of a direct current electrical machine comprises a support structure (1) defined by a pair of frame members (4) and beams (2), the latter being disposed around the center line (3) of the stator with the ends thereof affixed to the frame members (4), and a magnetic circuit (7) having a yoke (8) and pole pieces (9 and 10) secured to the yoke (8). The yoke is in the form of a single continuous band coiled into a cylindrical spiral, each turn of the spiral embracing by a wider side thereof all the beams (2) of the support structure (1).

TECHNICAL FIELD

The present invention relates to electrical engineering, and moreparticularly to stators of direct current electrical machines.

BACKGROUND ART

Modern technological advances call for the availability of fast responsedrives incorporating direct current electrical machines capable ofproviding variations in the rate of the armature current in excess of 30nominal values per second, as well as featuring high reliability andhigh specific characteristics in combination with minimal overall sizeand weight. Accordingly, this dictates higher structural requirements tothe stators of direct current electrical machines, viz. laminatedmagnetic circuits and optimal utilization of the interior at presetoverall dimensions.

Known in the art is a direct current machine stator (cf. British Pat.No. 1,432,700; Cl. H 02 K 1/18; published 1976) comprising a statorsupport having beams arranged around the center line of the stator, amagnetic circuit incorporating a laminated stator ring or yoke adaptedto receive the stator support beams, and pole pieces attached to theyoke. The yoke of the magnetic circuit is assembled bz means of pinsfrom separate L-shaped steel segments or plates disposed lingitudinallyof the center line of the stator, whereas the stator support furthercomprises cross beams welded to the longitudinal beams, the yoke beingpositioned essentially inside the stator support structure.

However, a disadvantage of this stator construction resides in thatlarge amounts of costly material, such as magnetic steel, are requiredfor the manufacture of the yoke due to irrationally arranged pattern ortailoring thereof.

Also, manual stacking the L-shaped plates into a yoke is a labourconsuming operation preventing a mechanized manufacture of the stator,which results in an inferior quality and reduced production efficiency.

DISCLOSURE OF THE INVENTION

The present invention is directed towards the provision of a directcurrent machine stator incorporating such a structural arrangement of ayoke as to permit an increase in the overall power of the machine,improve the reliability of the stator, raise the production efficiency,reduce the amount of materials consumed in the manufacture and ensurehigh rates of current variations in the armature.

This is attained by that in a direct current machine stator comprising asupport structure having beams disposed around the longitudinal centerline of the stator, a magnetic circuit incorporating a yoke adapted tocooperate with support beams, and pole pieces affixed to the yoke,according to the invention, the yoke is in the form of a continuous bandcoiled into a cylindrical roll or spiral with each turn of the spiralembracing by a wider side thereof all the support beams, the supportstructure further comprising a pair of frame members positioned at thebases of the cylindrical spiral and having the support beam ends securedthereto.

Preferably, at least one support frame is provided with at least oneaperture.

The present invention affords to have the stator manufacture mechanizedand automated.

Also, the invention permits to obtain the optimum configuration of thestator thereby enabling an increase in the overall power of the machineat preset size and weight requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with reference toa specific embodiment thereof taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a stepped longitudinal section of a direct current machinestator according to the invention;

FIG. 2 shows a cross-section on the line II--II in FIG. 1;

FIG. 3 is a general view of a frame member of the stator according tothe invention;

FIG. 4 is a partial view of a support structure according to theinvention, a partially cut-away representation;

FIG. 5 shows a section on the line V--V in FIG. 4;

FIG. 6 illustrates a fastening assembly of the starting portion of aband material of the stator according to the invention; and

FIG. 7 shows a section on the line VII--VIII in FIG. 6.

BEST MODE OF CARRYING OUT THE INVENTION

Stator of a direct current electrical machine comprises a supportstructure 1 (FIGS. 1 and 2) defined by four pairs of beams 2 disposedaround a longitudinal center line 3 of the stator, and two frame members4. Ends of the beams 2 are received into openings 5 (FIGS. 3 and 4)provided in the frame members 4 and welded to these frame members 4. Forimproved rigidity of the support structure 1 (FIGS. 2, 4 and 5) a plate6 is secured between each pair of the beams 2. The stator furthercomprises a magnetic circuit 7 (FIG. 1) incorporating a yoke 8 with endsides thereof accommodating the frames 4 of the support structure 1, andpole pieces 9 and I0 (FIG. 2). The yoke 8 is in the form of a polyhedronand made up of a continuous band 11 coiled into a cylindrical spiral.Each turn of the spiral embraces by a wider surface thereof all thebeams 2 of the support structure 1. Attached to each narrow outer sideof the yoke 8 is a plate 12. Each of the pole pieces 9 and I0 comprisesrespectively a core element 13 having an exitation winding 14 and a coreelement 15 having a winding 16 intended for compensating a reactiveelectromotive force arising during operation of the machine. Affixed tothe frame members 4 (FIG. 1) are spaces or boxes 17.

Represented in FIG. 6 is an assembly 18 for fastening the startingportion of the band stock 11. The assembly 18 further comprises screwclamps 19 and 20 connected therebetween and a bar 21 having the startingportion of the band stock 11 crimped therearound.

With reference to FIG. 7, there is shown an assembly 22 for fasteningthe end portion of the band stock 11 comprising a plate 23 attached tothe frame member 4 by a screw bolt 24.

Received through a threaded opening in the plate 23 is a holding bolt 25for holding by means of the plate 12 the end portion of the band 11defining the yoke 8. For monitoring the tightness of the coiled band 11(FIG. 2) wound around the beams 2 there are provided apertures 26 (FIGS.3 and 7) in the frame members 4.

The stator of a direct current electrical machine is assembled in thefollowing manner.

Assembled first is the support structure 1 (FIGS. 1, 2, 3 and 4). Thebeams 2 are inserted into the openings 5 of the frames 4 and weldedthereto. This is accompanied by securing the plates 6 (FIGS. 2, 4 and 5)to the beams 2 and the narrow sides of the frame members 4. Aftercompleting the assembly of the support structure 1, the starting portionof the band 11 is fixed between the screw clamps 19 and 20 (FIG. 6) andcrimped around the bar 21. Thereafter, the band 11 is coiled into acylindrical spiral around the beams 2 of the support structure 1 therebyobtaining the yoke 8. Tight winding of the coils is controlled throughthe apertures 26 (FIGS. 3 and 7). The end portion of the band 11 is heldin position by means of the plate 23 and the holding bolt 25 acting tofix the end portion of the band 11 through the plate 12. Thereupon,excess of the starting and end portions of the band 11 is cut-off to befollowed by removing the screw clamps 19 and 20 (FIG. 6), bar 21, plates23 (FIG. 7), bolts 24 and 25. The core elements 13 and 15 of the polepieces 9 and I0 respectively are then secured to the inner side of thethus obtained yoke 8 (FIG. 2) with mounted on the core elements windings14 and 16.

In view of the foregoing, the present invention makes it possible toreduce material waste during manufacture of the stator according to theinvention, which enables to improve the efficiency of utilization of thematerials consumed to 95%.

INDUSTRIAL APPLICABILITY

This invention can be advantageously applied in various fields of thenational economy, such as metallurgical, paper-making andmachine-building industries.

We claim:
 1. A direct current electrical machine stator comprising asupport structure having beams disposed around the longitudinal centerline of the stator, a magnetic circuit incorporating a yoke adapted tocooperate with support beams, and pole pieces affixed to the yoke,characterized in that the yoke (8) is in the form of a continuous bandcoiled into a cylindrical spiral with each turn of the spiral embracingby a wider side thereof all the support beams (2) of the supportstructure (1), the support structure (1) further comprising a pair offrame members (4) positioned at the bases of the cylindrical spiral andhaving ends of the support beams (2) of the support structure (1)secured thereto.
 2. A stator as claimed in claim 1, characterized inthat at least one frame member (4) of the support structure (1) isprovided with at least one aperture (26).